Prediction of bending springback of the medium-Mn steel considering elastic modulus attenuation
Prediction of bending springback of the medium-Mn steel considering elastic modulus attenuation
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DOI：
10.1016/j.jmapro.2021.04.074
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发表时间：
2021-05-10
影响因子：
6.2
通讯作者：
Dong, H.
中科院分区：
文献类型：
--
作者：
Chang, Y.;Wang, N.;Dong, H.
轻量化和安全性的提高是汽车零部件的发展要求。因此，对超高强度薄壁零件的需求更加迫切。但随着强度的提高，零件的回弹现象尤为严重，极大地影响了零件的成形质量。一般来说，汽车零件的回弹应控制在5%以内。因此，准确的回弹模拟和预测可以为超高强度汽车薄壁件的制造提供重要的支持。本文对第三代汽车用钢中锰钢的弯曲回弹进行了试验和模拟研究。通过拉伸试验，评价了高强高塑复合材料的综合力学性能。通过循环加卸载试验，分析了卸载弹性模量和非弹性恢复率随应变的变化规律。进一步建立了卸荷弹性模量与真塑性应变的相关模型，并求出了模型参数。在此基础上，进行了不同条件下的V形弯曲试验，分析了轧制方向、弯曲角度和凸模圆角半径对回弹的影响。轧制方向对回弹角的影响可以忽略不计。弯曲角度对回弹角有正向影响，而凸模圆角半径对回弹角有负向影响。最后，利用自定义的材料子程序，建立了中锰钢等弹性模量和变弹性模量的材料模型。对等弹性模量和变弹性模量V形弯曲试验进行了数值模拟，并与试验结果进行了比较。变弹性模量的模拟结果更接近于实验结果，证明了在中锰钢数值模拟中考虑卸载弹性模量变化的重要性。本文的研究结果有助于提高中锰钢零件回弹模拟的精度，促进其工业应用。
The improvement of lightweight and safety is the development requirement of automobile parts. Therefore, the demand of thin-walled parts with ultra-high strength is more urgent. However, with the increase of strength, the springback phenomenon of parts is particularly serious, which greatly affects the forming quality of parts. Generally, the springback of automobile parts should be controlled within 5%. Thus, the accurate simulation and prediction of springback can provide important support for the manufacture of ultra-high strength automobile thin-walled parts. In this paper, the bending springback of the medium-Mn steel, as one of the third-generation automobile steels, was studied based on experiment and simulation under different conditions. Tensile tests were carried out to evaluate comprehensive mechanical properties with high strength and high plasticity. Cyclic loading-unloading tests were conducted to analyze the changing rules of unloading elastic modulus and inelastic recovery with strain. The correlation model between unloading elastic modulus and true plastic strain was further established and the model parameters were obtained. Furthermore, V-shaped bending tests were carried out under different conditions to analyze the effects of rolling direction, bending angle, and punch fillet radius on springback. The effect of rolling direction on springback angle is negligible. The bending angle has a positive effect on springback angle, while the punch fillet radius has a negative effect. Finally, the material model with constant and variable elastic moduli were developed by using user-defined material subroutines for the mediumMn steel. V-shaped bending tests under constant and variable elastic moduli were simulated and compared with the experimental result. The simulated result with variable elastic modulus was closer to the experimental one, which proves the importance of considering the change of unloading elastic modulus in the numerical simulation of medium-Mn steel. The research result of this paper is helpful to enhance the simulation accuracy of springback of medium-Mn steel part and promote its industrial application.